Posts Tagged ‘Transit of Venus’

Q:  Why does the Transit of Venus have a special place in Australia’s history?
A:  Without it, Australia may have been a Portuguese or Dutch colony!

England may not have commissioned James Cook (later known as Captain Cook) to make the voyage to discover the great south land if there had been no Transit of Venus in 1769.  Much earlier, Dutch and Portuguese explorers had already struck Australia, but hadn’t realized it was a huge continent. Given a few more years, they’d have explored further and taken possession.  Luckily for England, Cook, in addition to being a master navigator, was also a skilled cartographer.  When he mapped the eastern seaboard of the land, he grasped the truth about its size.  He promptly landed in what is now Botany Bay, Sydney, stuck the Union Jack in the sand, and said to the astonished Aborigines: “This land now belongs to England”, or words to that effect.

Let’s go back a few more years.  In the mid 1700s, Europe was abuzz with the problem of calculating the distance from the earth to the sun.  Edmund Halley (of comet fame) suggested that if the Transit of Venus was carefully observed from two widely separated places on earth, mathematics could be used to work out the earth/sun distance. There were two Transits in the 18th century. The first transit in 1761 occurred during the peak of the Seven Years’ War (1756-1763). A spirit of scientific collaboration was difficult to promote during the conflict. Despite that, many countries sent out expeditions, none of which succeeded.

The next transit was due eight years later in 1769.  The decade was one of great political rivalry, but both the English and French decided to send expeditions to observe the Transit of Venus.

For the 1769 Transit, England sent Cook to Tahiti to make observations. He was appointed master of the sailing ship Endeavour, and provided with a portable observatory to set up in Tahiti.  His mission was clear: the Endeavour was on a scientific quest. 

Sketch of portable observatory used by Cook

From Wikipedia: (now in public domain) Sketch of portable observatory used by Cook (Click on image to enlarge)

The British government, however, was smart.  The Admiralty gave Cook a sealed envelope that he was to open only after making observations of the Transit of Venus in Tahiti.  Cook did not know its contents. 

Cook set sail months earlier to be in time for the great event.  He reached Tahiti and made observations of the Transit of Venus.  The next day he opened the sealed envelope, and found new orders: he was to sail south to discover Terra Australis incognita: the unknown south land.  His new project was definitely non-scientific in nature.  

So Cook’s first voyage was exceptionally successful.  He personally viewed the Transit of Venus at Tahiti, then went on to discover the land that became modern Australia.  No wonder Australians have had a special interest in the subsequent Transits of Venus in 1874, 1882, 2004 and 2012.  

For the 1874 Transit, Sydney Observatory ordered a special telescope from Europe. (More details later in this blog.)  Just in case Sydney weather was overcast on the day of transit, Henry Chamberlain Russell, the director of the Observatory, set up three other viewing sites at Woodford in the Blue Mountains, Eden on the South coast and Goulburn on the Southern Tablelands.  Later, Russell wrote a book that became a classic in Astronomy:  “Observations of the Transit of Venus, 9 December 1874.”   The current director of Sydney Observatory, Nick Lomb, a Transit enthusiast, has given a sweeping historical and scientific account in his book:  “Transit of Venus: 1631 to the Present.”

Fast forward to 2012…

Keen astronomers, and the not-so-keen, were caught up in Transit fever in Australia for many months. The Transit was to be visible from most parts of Australia, and the big cities of the east – Melbourne, Sydney and Brisbane – could view the entire transit from beginning to end.  Then there was the added thrill that we were lucky to be alive to witness the transit, for the next one will not happen for another 105 years.  And finally, we Australians speak English and follow the Westminster system of democracy all because Cook came south after observing the Transit of Venus in Tahiti in 1769. 

“Are you going to watch the Transit?” was the most common greeting in recent weeks, followed up by, “But what’s the weather going to be like?” The predictions were dire!

5 June 2012

When Snoopy, Charlie Brown’s canine friend wrote, “It was a dark and stormy night …” he could have been writing about the night of 5 June. The wind was howling, the seas were roaring (waves 7 metres high were hitting the coast) and hopes of viewing anything at all on the morrow were dismal. 

I was tempted to say DRAT – Dark Rainy And Tempestuous!

But, so as not to jinx the 6th, we went to bed with optimism. We had booked tickets at Sydney Observatory and we were going, come hell or high water. The main actors would be on stage in the sky, and to even imagine the curtains would be closed, was not worth thinking about!

6 June 2012 

We woke up early and when I looked out of Bedroom Observatory, the sight that greeted me was not encouraging. But the tiny piece of brightness was enough for me! “It’s clearing up,” I said to Dom.

The sky at 6 am

The sky at 6 am (Click on image to enlarge)

My optimism was rewarded. Just before we left, the sky brightened and there was an encouraging ray from the sun. Can you see it?

Sky at 7 am

And we were off. I was confident we would see the much anticipated celestial rendezvous. Our time slot at the Observatory was 10 am to 12.30 pm.

We arrived at Circular Quay and walked up Observatory Hill, well in time.  The sight that greeted us confirmed that there were many Sydneysiders who were as eager as we were.  Even more eager in fact for the people you see in the picture were from the earlier, stormier time slot. 

Viewers at the Observatory

The flags on the Observatory mast announced the big event.  You’ll recognize the planet Venus flag, but look closely and you’ll see the yellow Transit-of-Venus flag, specially made for the occasion.

Flag of the Transit of Venus

At the gate the special event sign greeted us:

Gate at Observatory

Gate at Observatory

We received our sunglasses and yellow wrist bands to mark our time slot. As Dom put on his wrist band he joked: “Just in case I get lost and my mother comes looking for me.” Our spirits were buoyant!


Wristband (Click to enlarge)

My brother Neville joined us and we lined up at the first telescope. By now Venus was at 5 o’clock on the sun. The view was reversed by the telescope so, it was up top at the 1 o’clock position.

Neville at the telescope

Neville at the telescope (Click on image to enlarge)

 I viewed the Transit through binoculars.

Daphne looking at the Transit

Daphne looking at the Transit (Click on image to enlarge)

I now had ocular proof! Venus was a clear black dot. We could see the sun spots too!

The Observatory has observed all the Transits of Venus which have occurred after Captain Cook made his historic viewing. This exhibit shows the path of Venus in the three observations, 1874, 2004 and 2012.

Transit of Venus Exhibit

Transit of Venus Exhibit (Click on image to enlarge)

Sign in Observatory

No kidding! After all, Venus is our Earth’s sister and, as it is an inner planet, we can see it  crossing the face of the Sun. Venus is a third of the distance between us and the Sun.

Its orbit is not exactly on the same plane as Earth’s orbit. It is inclined by 3.4° relative to the Earth’s, and so Venus usually appears to us to pass under (or over) the Sun. It completes an orbit every 224.65 Earth days. Astronomers calculate mathematically exactly when the next Transit will occur.

The historic 1874 telescope in the dome is seriously impressive in size and optics!  And it is cared for with religious diligence.  As we lined up on the stairs, a squall of rain came, and the Observatory staff closed the dome immediately.  That’s why my picture is so dark.

The 1874 telescope

The 1874 telescope (Click on image to enlarge)

 If you are interested in the details, this is a H9886  11.4 inch equatorial refracting telescope; optics and brass tubes by Hugo Schroeder, Hamburg, Germany.

Dom gets an eyeful of Venus…

Dom at the big telescope

Dom at the big telescope (Click on image to enlarge)

Our next stop was for a talk in the marquee where Professor Iver H Cairns, Professor of Space Physics at Sydney University, spoke about sunspots.

12.15pm:  Live screens showed us the current state of transit. Venus had half way to go.

Transit at about 12 noon

Transit at about 12 noon (Click on image to enlarge)

Near the end of our time slot at the Observatory, the clouds came over and a drizzle forced Observatory staff to cover up all the telescopes and binoculars.

How lucky we were! We actually saw the Transit despite clouds, rain and wind. 

Time to reward ourselves we thought, so we walked over to a nearby cafeteria and warmed ourselves with some lunch.

Post Script: We went away with a reminder from the Observatory that 2012 is the Year of the Sun. We’ve had the Annular Eclipse of the Sun (not in Australia), the Transit of Venus, and we can look forward to the Total Eclipse of the Sun in Cairns in November.

Reminder of the Total Eclipse in November

Reminder of the Total Eclipse in November

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